DERIVATIVES - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Derivative [Line Items]
Derivative liability position net	$ 0		$ 0
Derivative asset position net	12,600		12,600
Collateral received against obligations in net asset position	12,300		12,300
Collateral posted in net liability position	0		0
Interest rate swaps | Derivative designated as a cash flow hedge
Derivative [Line Items]
Notional amounts	290,000		290,000		$ 240,000
Interest rate swaps | Derivative designated as a cash flow hedge | Federal Home Loan Bank of New York
Derivative [Line Items]
Interest (income) expense on derivative	$ (466)	$ (344)	(1,000)	$ (279)
Reduction to interest expense			(466)
Reclassified estimated decrease in interest expense			$ 400